| 摘要 |
<p>A garage door opening and closing apparatus (10) having improved operational safety is diclosed. The apparatus includes a control circuit (101) which responds to a number of input stimuli to generate commands to open and close a garage door (14) as well as to stop garage door movement. Three relays (130, 131, 132) respond to the commands via drive circuitry (147) to actually connect door operating voltages to the windings (225, 227) of a door controlling motor (211). By redundancies in the operation of the three relays, faults in the operation of those relays result in safe door operating conditions. Additionally, the control circuitry upon issuing a door stop command, performs a test to determine whether or not the door is still moving. If the door is still moving, doorup commands are generated by the control circuitry to place the door in a safe position.</p> |
